O7‐2: Subunit immunization with outer membrane protein potentially protects broadly against multidrug‐resistant gram‐negative bacillus

ABSTRACT The outer membrane of Treponema pallidum, the noncultivable agent of venereal syphilis, contains a paucity of protein(s) which has yet to be definitively identified. In contrast, the outer membranes of gram-negative bacteria contain abundant immunogenic membrane-spanning β-barrel proteins mainly involved in nutrient transport. The absence of orthologs of gram-negative porins and outer membrane nutrient-specific transporters in the T. pallidum genome predicts that nutrient transport across the outer membrane must differ fundamentally in T. pallidum and gram-negative bacteria. Here we describe a T. pallidum outer membrane protein (TP0453) that, in contrast to all integral outer membrane proteins of known structure, lacks extensive β-sheet structure and does not traverse the outer membrane to become surface exposed. TP0453 is a lipoprotein with an amphiphilic polypeptide containing multiple membrane-inserting, amphipathic α-helices. Insertion of the recombinant, nonlipidated protein into artificial membranes results in bilayer destabilization and enhanced permeability. Our findings lead us to hypothesize that TP0453 is a novel type of bacterial outer membrane protein which may render the T. pallidum outer membrane permeable to nutrients while remaining inaccessible to antibody.

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Channel Formation by CarO, the Carbapenem Resistance-Associated Outer Membrane Protein of Acinetobacter baumannii

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.12.4876-4883.2005 ◽

2005 ◽

Vol 49 (12) ◽

pp. 4876-4883 ◽

Cited By ~ 73

Author(s):

Axel Siroy ◽

Virginie Molle ◽

Christelle Lemaître-Guillier ◽

David Vallenet ◽

Martine Pestel-Caron ◽

...

Keyword(s):

Membrane Protein ◽

Acinetobacter Baumannii ◽

Outer Membrane ◽

Lipid Bilayers ◽

Outer Membrane Protein ◽

Carbapenem Resistance ◽

Protein Band ◽

Multidrug Resistant ◽

Channel Formation ◽

Artificial Lipid Bilayers

ABSTRACT It has been recently shown that resistance to both imipenem and meropenem in multidrug-resistant clinical strains of Acinetobacter baumannii is associated with the loss of a heat-modifiable 25/29-kDa outer membrane protein, called CarO. This study aimed to investigate the channel-forming properties of CarO. Mass spectrometry analyses of this protein band detected another 25-kDa protein (called Omp25), together with CarO. Both proteins presented similar physicochemical parameters (M w and pI). We overproduced and purified the two polypeptides as His-tagged recombinant proteins. Circular dichroism analyses demonstrated that the secondary structure of these proteins was mainly a β-strand conformation with spectra typical of porins. We studied the channel-forming properties of proteins by reconstitution into artificial lipid bilayers. In these conditions, CarO induced ion channels with a conductance value of 110 pS in 1 M KCl, whereas the Omp25 protein did not form any channels, despite its suggested porin function. The pores formed by CarO showed a slight cationic selectivity and no voltage closure. No specific imipenem binding site was found in CarO, and this protein would rather form unspecific monomeric channels.

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Multidrug-resistant klebsiella pneumoniae-induced sepsis with multiple abscesses: A case report

Journal of Clinical Images and Medical Case Reports ◽

10.52768/2766-7820/1226 ◽

2021 ◽

Vol 2 (4) ◽

Author(s):

Ye Xiong ◽

◽

Jianrong Huang ◽

Keyword(s):

Case Report ◽

Antimicrobial Resistance ◽

Klebsiella Pneumoniae ◽

Oral Cavity ◽

Multidrug Resistant ◽

Drug Resistant ◽

Human Intestine ◽

Gram Negative ◽

Negative Bacillus ◽

Gram Negative Bacillus

Klebsiella pneumoniae, a Gram-negative bacillus which exists widely in nature, is generally colonized in the human intestine and oral cavity and does not cause disease [1]. However, the emergence and global expansion of hypervirulent and multidrug-resistant clones of K. pneumoniae have been increasingly reported in community-acquired and nosocomial infections. Management of antimicrobial resistance in multi-drug-resistant-K. pneumoniae (MDR-KP) is a major challenge for clinicians [2]. The optimal treatment option for MDR-KP infections is still not well established, which brings huge challenges to clinical treatment [2].

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Assembly and Channel Opening of Outer Membrane Protein in Tripartite Drug Efflux Pumps of Gram-negative Bacteria

Journal of Biological Chemistry ◽

10.1074/jbc.m111.329375 ◽

2012 ◽

Vol 287 (15) ◽

pp. 11740-11750 ◽

Cited By ~ 33

Author(s):

Yongbin Xu ◽

Arne Moeller ◽

So-Young Jun ◽

Minho Le ◽

Bo-Young Yoon ◽

...

Keyword(s):

Membrane Protein ◽

Fusion Protein ◽

Membrane Fusion ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Membrane Fusion Protein ◽

Docking Model ◽

Channel Opening

Gram-negative bacteria are capable of expelling diverse xenobiotic substances from within the cell by use of three-component efflux pumps in which the energy-activated inner membrane transporter is connected to the outer membrane channel protein via the membrane fusion protein. In this work, we describe the crystal structure of the membrane fusion protein MexA from the Pseudomonas aeruginosa MexAB-OprM pump in the hexameric ring arrangement. Electron microscopy study on the chimeric complex of MexA and the outer membrane protein OprM reveals that MexA makes a tip-to-tip interaction with OprM, which suggests a docking model for MexA and OprM. This docking model agrees well with genetic results and depicts detailed interactions. Opening of the OprM channel is accompanied by the simultaneous exposure of a protein structure resembling a six-bladed cogwheel, which intermeshes with the complementary cogwheel structure in the MexA hexamer. Taken together, we suggest an assembly and channel opening model for the MexAB-OprM pump. This study provides a better understanding of multidrug resistance in Gram-negative bacteria.

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